COMPX201 WEEK 1 TUTORIAL SLIDES Notes

Tutorial 1: Sets

Course Information

• Course Codes: COMPX201-26A & COMPX241-26A

Tutorial Marking Scheme

• Tutorials contribute 10% to the overall mark.
• There are ten weekly tutorials to attend.
• Procedure for Signing Off:
    - Write your name, student ID, and a question on an index card.
    - Submit this index card to the tutor at the start of the tutorial.
    - Questions can pertain to:
      - Lecture topics
      - Assignments
      - Topics about which you wish to know more or want to explore
    - It is encouraged to write your questions in advance, such as during lectures.

Icebreaker Activity

Assignment 1: Card Game Implementation

• Task: Implement a card game in Java using Linked Lists.
• Rules of the Game:
    - Each player draws 5 cards to start.
    - A player can play a card if:
      - The suit matches the most recently played card.
      - The number is either +1 or -1 of the most recently played card.
    - If a player cannot play a card, they must draw another card from the deck.
    - The winner is the player that empties their hand first.

Defining Data Structures

What is a Set?

• A set is a fundamental data structure that holds a collection of distinct elements. Sets do not allow duplicate values and provide operations to perform various set-related tasks.

Use Cases for Sets

Problems Where Sets are Helpful

• Sets are beneficial for scenarios such as:
    - Unique item tracking: Storing unique elements like usernames, product IDs, or tags.
    - Membership testing: Quickly checking if an element exists in a collection.
    - Eliminating duplicates: Filtering lists to remove duplicate entries.
    - Mathematical operations: Performing union, intersection, and difference operations on collections of data.

Set Operations

Example with Sets A and B

• Assuming we have two sets:
    - Set A: $A = {1, 2, 3, 4, 5}$
    - Set B: $B = {1, 3, 5, 7, 9}$

Operations

• Define the union of sets A and B:
    - $x = A \cup B$
• Define the intersection of sets A and B:
    - $y = A \cap B$
• Define the difference of sets A and B:
    - $z = A \setminus B$

Java Implementation Examples

Difference Method

• Write the Java code for a method to compute the difference of two sets:
    - Method signature: SimpleSet difference(SimpleSet s)
    - You may use the remove(int i) method in the SimpleSet class.

Movie Recommendation Filtering

• Complete the code for a method that returns a list of recommended movies that have not been watched:
    - Method Signature:
  java public MovieSet filterRecommendations(MovieSet rec, MovieSet watched)   
    - This method will filter the rec set based on the watched set.

Set Application: Checking for Equivalence

• Implement a custom function to check if two sets are equivalent.
    - Example sets to check:
      - Set 1: ${2, 1, 5, 3, 7}$
      - Set 2: ${2, 1, 5, 3}$
    - This entails determining if both sets contain the same elements, irrespective of order or duplicates.